Digital broadcasting transmission/reception system capable of improving receiving and equalizing performance and signal processing method thereof

ABSTRACT

A digital broadcast transmitting and receiving system and a signal processing method thereof that improves the receiving performance of the system. A digital broadcast transmitter includes a randomizer to receive and randomize a data stream into a specified position of which stuff bytes are inserted, a replacement sequence generator to generate known data including a predefined sequence, a stuff-byte exchange unit to insert the known data into the specified position of the data stream into which stuff bytes are inserted, an encoder to encode the data stream output from the stuff-byte exchange unit for an error correction, and a transmission unit to modulate the encoded data stream, RF-convert the modulated data stream and transmit the RF-converted data. The digital broadcast receiving performance is improved even in an inferior multi-path channel by detecting the known data from the received transmission and using the known data for synchronization and equalization in a digital broadcast receiver.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 10/578,094,filed on May 3, 2006, which claims the benefit of PCT InternationalPatent Application No. PCT/KR 2005/001940 filed Jun. 23, 2005, andKorean Patent Application No. 2004-47153 filed Jun. 23, 2004 in theKorean Intellectual Property Office, the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An aspect of the present invention relates to a digital broadcastingtransmission/reception system, and more specifically, to a digitalbroadcasting transmission/reception system generating stuff byte in aMoving Picture Experts Group-2 transport stream (MPEG-2 TS), andoperating and transmitting a pattern of known data using the stuff byteto improve reception performance and equalization performance of areception system and a signal processing method thereof.

2. Description of the Related Art

The Advanced Television Systems Committee Vestigial Sideband (ATSC VSB)method, a U.S.-oriented terrestrial waves digital broadcasting system,is a single carrier method that uses a field sync by 312 segment unit.Accordingly, reception performance is not good in poor channels,especially in a Doppler fading channel.

FIG. 1 is a block diagram of a transmitter/receiver of a generalU.S.-oriented terrestrial waves digital broadcasting system according tothe ATSC digital television (DTV) standards.

The digital broadcasting transmitter of FIG. 1 has a data randomizer(110) for randomizing an MPEG-2 TS, an Reed-Solomon (RS) encoder (120)of a concatenated coder form for correcting errors generated bychannels, an interleaver (130), and a ⅔ rate trellis encoder (140). Theencoded data is mapped in 8 level symbols and field syncs and segmentsyncs are inserted into the data as shown in FIG. 2. After that, pilotsare inserted into the data, the data is VSB-modulated, upconverted intoRF and transmitted.

Meanwhile, the digital broadcasting receiver of FIG. 1 lowers the RFsignal to baseband, demodulates and equalizes the lowered signal,performs channel decoding, and restores the original signal in a reverseorder of the digital broadcasting transmitter. FIG. 2 shows a vestigialsideband (VSB) data frame of the U.S.-oriented DTV system. In FIG. 2,one frame consists of two fields. One of the fields includes the 312data segments and the field sync segment. One segment has segment syncsof four symbols and data symbols of 828 symbols.

As shown in FIG. 1, the digital broadcasting transmitter randomizes theMPEG-2 TS through the randomizer (110). The randomized data isouter-coded through the RS encoder (120) which is an outer coder, andthe outer-coded data is dispersed through the interleaver (130). Theinterleaved data is inner-coded by 12 symbol unit through the trellisencoder (140), and the inner-coded data is mapped in an 8 level symboland inserted with the field syncs and segment syncs as shown in FIG. 2.Thereafter, the data includes DC offset to generate the pilot, and thedata is VSB-modulated, upconverted to an RF signal and transmitted.

Meanwhile, the digital broadcasting receiver of FIG. 1 converts an RFsignal received through a channel into a baseband signal through atuner/IF (not shown). The baseband signal is synchronization-detectedand demodulated through a demodulator (210), and any distortion bymulti-path channel is compensated through an equalizer (220). Theequalized signal is error-corrected and decoded into symbol data througha viterbi decoder (230). The decoded data, which has been dispersed bythe interleaver (130) of the transmitter, is rearranged through ade-interleaver (240), and the deinterleaved data is error-correctedthrough an RS decoder (250). The error-corrected data is de-randomizedthrough a derandomizer (260) and output into an MPEG-2 TS.

In the VSB data frame of the US-oriented terrestrial waves DTV system ofFIG. 2, one segment corresponds to one MPEG-2 packet. In FIG. 2, thesegment sync and field sync, which are sync signals, are used forsynchronization and equalization. The field sync and segment sync areknown sequences and used as training data in the equalizer.

The VSB method of the U.S.-oriented terrestrial waves digital televisionsystem of FIG. 1 is a single carrier system and has the capacity toremove multipath in a multipath fading channel with Doppler. However, ifthe known sequence such as a field sync is used a lot, it becomes easierto estimate the channel and compensate the signal distorted by multipathin the equalizer using the known sequence.

However, as shown in the VSB data frame of the U.S.-oriented terrestrialwaves digital television system of FIG. 2, a field sync which is a knownsequence appears in every 313th segment. This is not frequent so thecapacity to remove the multipath and equalize the received signal usingthis, is low.

SUMMARY OF THE INVENTION

An aspect of the present invention is to provide a digital broadcastingtransmission/reception system to improve reception performance andequalization performance of a reception system by adding a predefinedknown sequence, manipulating a pattern and transmitting a signal in atransmission system and a signal processing method, and a digitalbroadcasting reception system corresponding to the above and a signalprocessing method thereof.

A digital broadcasting system including a digital broadcastingtransmitter encoding a data stream including stuff bytes at a certainlocation, modulating, RC-converting and transmitting the encoded datastream; and a digital broadcasting receiver receiving the encoded datastream, demodulating the encoded data stream into a baseband signal,detecting the known data from the demodulated signal, and equalizing thedemodulated signal using the detected known data.

According to another aspect of the present invention, there is provideda signal processing method of a digital broadcasting system includesencoding a data stream including stuff bytes at a certain location,modulating, RC-converting and transmitting the encoded data stream; andreceiving the encoded data stream, demodulating the encoded data streaminto a baseband signal, detecting the known data from the demodulatedsignal, and equalizing the demodulated signal using the detected knowndata.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a block diagram illustrating a transmitter of a generalU.S.-oriented terrestrial digital broadcasting system;

FIG. 2 is a view of a frame structure of ATSC VSB data;

FIG. 3 is a view of a frame structure of a TS packet;

FIG. 4 is a view of a frame structure of a TS packet including a stuffbyte;

FIG. 5 is a block diagram of a digital broadcastingtransmission/reception system according to an embodiment of the presentinvention;

FIG. 6 is a view of a format of the data input to the randomizer of FIG.5;

FIG. 7 is a view of a format of the data output from the randomizer ofFIG. 5;

FIG. 8 is a view of a format of the data output from the RS encoder ofFIG. 5;

FIG. 9 is a view of a format of the data output from the datainterleaver of FIG. 5;

FIG. 10 is a view of a format of the data output from the trellisencoder of FIG. 5;

FIG. 11 is a view of a format of the data output from an RS re-encoderaccording to trellis initialization of the known sequence section;

FIG. 12 is a block diagram illustrating a digital broadcastingtransmission/reception system according to another embodiment of thepresent invention; and

FIG. 13 is a view illustrating the known symbol location detector/knowndata output of FIG. 5.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

FIG. 3 shows a frame structure of a TS packet and FIG. 4 shows a framestructure of a TS packet with a stuff byte. The TS packet of FIG. 3includes an MPEG-2 header, and an adaptation field or ES data. Accordingto an aspect of the present invention, stuff bytes are inserted in apacket as illustrated in FIG. 4 so that all the TS streams haveadaptation fields.

That is, the MPEG-2 TS packet of FIG. 4 is an MPEG-2 packet of 188 bytesand consists of an MPEG-2 header, an adaptation field and ES or payloaddata. The header includes 4 bytes with MPEG syncs, the adaptation fieldincludes an adaptation field length section of 1 byte indicating thelength of the adaptation field, an adaptation field data section havingother information of 1 byte and stuff bytes of N bytes, and the payloaddata includes ES data of 188−(4+2+n) bytes.

FIG. 5 is a block diagram illustrating a digital broadcastingtransmission/reception system according to an embodiment of the presentinvention. In FIG. 5, the digital broadcasting transmitter receives anMPEG-2 packet TS having the packet structure of FIG. 4 through a TSmultiplexer (not shown).

In FIG. 5, the digital broadcasting transmitter has a data randomizer(310) for randomizing the input TS stream, a stuff byte replacer (315)for replacing the stuff byte of the randomized data with a particularsequence, an RS encoder (320) constructing the data output from thestuff byte replacer (315) in the concatenated code form to correcterrors generated by channels, an interleaver (330) for interleaving thedata, a packet buffer (325) storing the RS-encoded reference data toinitialize a memory of a trellis encoder (340) and replacing theprevious value with an initialized value, an RS re-encoder & replaceparity (335) performing RS-encoding using the altered value, generatinga parity and inputting the parity to the trellis encoder (340), thetrellis encoder (340) converting the interleaved data into symbols andperforming ⅔ rate trellis encoding and 8 level symbol mapping, amultiplexer (350) inserting field syncs and segment syncs as shown inFIG. 2, a transmission part (360) for inserting a pilot, performingVSB-modulation, upconverting the data into RF and transmitting the data,and a control signal generator (370) for generating a signal to controldata processing.

In FIG. 5, the digital broadcasting receiver goes through a reverseorder of the transmitter and the receiver includes a demodulator (410)lowering the RF signal to baseband and demodulating the signal, anequalizer (420) removing inter-symbol interference, a Viterbi decoder(430) for performing error-correction and decoding, a de-interleaver(440), an RS decoder (450), and a de-randomizer (460). Additionally, thereceiver further includes a known symbol location detector/known symboloutput (470) detecting and outputting the location of the known symbolfrom the demodulated data.

Further, FIG. 13 is a block diagram illustrating the known symbollocation detector/known symbol output (470) in detail, and the knownsymbol location detector/known symbol output (470) includes a knownsymbol number detector (471), a segment flag generator (473), a trellisinterleaver (475) and a known data extractor (477).

In the digital broadcasting transmitter, if the information of thenumber of stuff bytes is inserted in the reserved part of the field syncdata segment section, the known symbol number detector (471) of theknown symbol location detector/known symbol output (470) of the receiverdetects the information of the number of the known data, the segmentflag generator (473) and trellis interleaver (475) find the informationof the location of the known symbol based on the detected information,the known data extractor (477) outputs the known data according to theacquired information on the location, and the known data is used toimprove reception performance of the receiver. If the information of thenumber of the stuff bytes is acquired, as the location of stuff bytes isalways fixed, the segment flag generator (473) and trellis interleaver(475) can be implemented using a counter and control logic.

Meanwhile, an MPEG-2 packet TS having the packet structure of FIG. 4 isinput to the randomizer (310) through the TS multiplexer (not shown),randomized, replaced with a particular sequence for the stuff bytes bythe stuff byte replacer (315) and output. The output data is outer-codedthrough the RS encoder (320) to correct errors by channels and theouter-coded data is dispersed through the interleaver (330).

Subsequently, the interleaved data is inner-coded by a 12 symbol unitthrough the trellis encoder (340). The inner-coded data is mapped in 8level symbols and the field syncs and segment syncs are inserted asshown in FIG. 10 by the multiplexer (350). Thereafter, the data includesa DC offset to generate a pilot and the data is VSB-modulated,up-converted into RF and transmitted.

Meanwhile, the control signal generator (370) detects the adaptationfield length of FIG. 4, and generates and outputs a flag signal toindicate the location of stuff bytes or known sequence data based on thedetected result.

Further, in FIG. 5, the trellis encoder (340) performs initialization of12 trellis encoder at the beginning location of the known sequence, forexample, in order for the value of the memory element of the encoder tobecome ‘00’. The sequence altered by the initialization replaces thevalue stored in the packet buffer (325) and the new parity generated bythe RS re-encoder & replace parity (250) replaces the value of theoriginal parity location input to the trellis encoder (340) so that theinitialization is performed.

FIG. 6 to FIG. 10 show data formats while an MPEG-2 packet with stuffbytes passes through channel encoder blocks of the digital broadcastingtransmitter.

FIG. 6 shows a format of the data input to the randomizer (310) and FIG.7 shows a data format after replacing n stuff bytes of the randomizeddata with particular sequence data. FIG. 8 shows a data format of theRS-encoded data added with RS parity and FIG. 9 shows a data format ofthe data output from the interleaver (330).

Further, FIG. 10 shows a format of the 12 symbol interleaved data outputfrom the trellis encoder (340). FIG. 11 is a format of the data whoseparity is restructured by the RS re-encoder & replace parity (335) ofFIG. 3. In FIG. 10, one field includes six convolutional interleavers,so there are six sequences with stuff bytes. That is, if a TS includesstuff bytes of 10 bytes, one field has known sequences of 10*6=60. Ifthe trellis encoder (340) is initialized at the beginning location ofthe known sequence, the output parity of the RS encoder (320) is alteredby the value of initialization and trellis encoding is performed byupdating with the altered parity.

The MPEG-2 packet of FIG. 6 is dispersed by 52 units by the interleaver(330) as shown in FIG. 9. The data located in the same byte of theMPEG-2 packet constructs the same column as shown in FIG. 9 after datainterleaving. Additionally, the interleaved data are12-symbol-interleaved by the trellis encoder (230) as shown in FIG. 10.That is, the data of the same location in MPEG-2 packets constructalmost one data segment as shown in FIG. 10 after trellis encoding.Therefore, if a particular part of an MPEG-2 packet is continuouslyadded with stuff bytes, randomized, replaced with a particular sequenceand trellis-encoded, the stuff bytes form one data segment which is aknown signal and a digital broadcasting receiver uses the known signalto improve reception performance.

FIG. 11 shows a data format after RS re-encoding and parityrestructuring by the RS re-encoder & replace parity (335) of FIG. 5.That is, if the trellis encoder (340) is initialized at the beginninglocation of a sequence of the known symbol, output parity of the RSencoder (320) is altered by the value of the initialization and trellisencoding is performed by being updated with the altered parity so thatthere is no problem in decoding of the RS decoder of a digitalbroadcasting receiver which will be described below. That is, thetrellis encoder is initialized in order for the trellis-encoded data toform a regular sequence during the known symbol sequence section, RSencoding is performed to replace the data of the initialization locationso that parity is altered and the altered parity replaces the originalparity. FIG. 11 shows the data format.

Meanwhile, the demodulator (410) of a digital broadcasting receiverdownconverts the RF signal received through a channel into a basebandsignal through a tuner/IF (not shown), and the converted baseband signalis sync-detected and demodulated. The equalizer (420) compensateschannel distortion by multipath of channels in the demodulated signal.

Meanwhile, a known symbol location detector/known data output (470)detects information on the number of stuff bytes inserted in thereserved section of field sync data segment section, acquiresinformation on the location of the known symbol and outputs the knowndata from the acquired information on the location.

In a digital broadcasting transmitter, if the information on the numberof stuff bytes is inserted in a reserved section of a field sync datasegment section, a known symbol number detector (471) of a known symbollocation detector/known data output (470) of the digital broadcastingreceiver detects the information on the number of the known data, asegment flag generator (473) and trellis interleaver (475) find thelocation information of the known symbol based on the information, and aknown data extractor (477) outputs and uses the known data from theacquired information to improve reception performance of the digitalbroadcasting receiver. As the location of stuff bytes is always fixed,if the information on the number of the stuff bytes is acquired, thesegment flag generator (473) and trellis interleaver (475) can beimplemented using a counter and control logic.

Meanwhile, the equalized signal by the equalizer (420) iserror-corrected through the Viterbi decoder (430) and decoded in symboldata. The decoded data rearranges the data dispersed by the interleaver(330) of the digital broadcasting transmitter through the deinterleaver(440). The deinterleaved data is error-corrected through the RS decoder(450). The error-corrected data is derandomized through the derandomizer(460).

FIG. 12 is a block diagram illustrating a digital broadcastingtransmission/reception system according to another embodiment of thepresent invention. In FIG. 12, the digital broadcasting transmitter hasa randomizer (510) for randomizing data of the input TS stream, a stuffbyte replacer (515) for replacing the stuff byte of the randomized datawith a particular sequence generated in a replacement sequence generator(513), an RS encoder for constructing the data output from the stuffbyte replacer (515) in the concatenated code to correct errors generatedby channels, an interleaver (530) for interleaving the data, a packetbuffer (525) for storing the RS-encoded reference data to initialize amemory of the trellis encoder (540) and replacing the stuff byte with aninitialized value, an RS re-encoder & replace parity (535) forperforming RS-encoding using the altered value to generate parity andinputting the data to the trellis encoder (540), the trellis encoder(540) for converting the interleaved data into a symbol and performing ⅔trellis encoding and 8 level symbol mapping, a multiplexer (550) forinserting a field sync and segment sync as in the data format of FIG. 2,a transmission part (560) for inserting a pilot, performingVSB-modulation, converting the data into RF and transmitting the data,and a control signal generator (570) for generating a signal to controldata processing.

In FIG. 12, the digital broadcasting receiver follows a reverse order ofthe transmitter and includes a demodulator (610) for lowering the RFsignal to baseband and demodulating it, an equalizer (620) for deletinginter-symbol interference, a Viterbi decoder (630) for error-correctingand decoding, a deinterleaver (640), an RS decoder (650), and aderandomizer (660). Additionally, the receiver further includes a knownsymbol location detector/output (670) for detecting and outputting thelocation of the known symbol from the demodulated data.

The function and operation of each component of the digital broadcastingtransmission/reception system of FIG. 12 is similar to the components ofFIG. 5. Therefore, a detailed description of the function and operationis omitted and the difference will be described.

A stuff byte replacer (515) replaces stuff bytes of the data randomizedby the randomizer (510) with a particular sequence and outputs the data.In this case, a pattern of the particular sequence may be preferablyadjusted in order for the symbols mapped through the trellis encoder(540) to be well operated by the equalizer (620).

Therefore, according to another embodiment of the present invention, thedigital broadcasting transmitter further includes the replacementsequence generator (513) for generating a particular sequence to replacethe stuff bytes and providing the particular sequence to the stuff bytereplacer (515) in order for the pattern of the known sequence generatedby replacing the stuff bytes to well operate the equalizer (620).

According to another embodiment of the present invention the replacementsequence generator (513), and a parity reconstruction (535) of thetransmitter and a known data detector (670) of the receiver operatedifferently from the digital broadcasting transmission/reception systemof FIG. 5.

The replacement sequence generator (513) includes a memory (not shown)for storing the particular sequence to replace the stuff bytes in thestuff byte replacer (515) and a circuit (not shown) for controlling amemory address.

If the sequence pattern of the known data of FIG. 9 and FIG. 10 has arandom pattern without DC offset, operation performance of the equalizercan be improved. Accordingly, the replacement sequence generator (513)may preferably generate a particular sequence to replace the stuff bytesso that the sequence pattern of the known data mapped after trellisencoding of the trellis encoder (540) in the stuff byte replacer (515)has the random pattern without DC offset.

First, in order for the sequence of the known data to have a desirablepattern, the memory value of the trellis encoder (540) has to beinitialized.

The compatibility is maintained with the existing receiver and thememory value of the trellis encoder (340) is initialized by the packetbuffer (325) and RS re-encoder & replace parity (335) of FIG. 5.According to a method of an embodiment of the present invention, themethod initializes the memory value of the trellis encoder (340) of partof the stuff bytes according to the number of stuff bytes instead of theentire stuff bytes in order to be compatible with the existing receiver.Accordingly, the initialized stuff bytes can limitedly have a desirablepattern.

Therefore, in another embodiment of the present invention, the functionof initializing a memory value of the trellis encoder (540) for theentire stuff bytes, is added to the RS re-encoder & replace parity(535). That is, the RS re-encoder & replace parity (535) is compatiblewith the existing receiver and initializes the memory value of thetrellis encoder (540), according to an embodiment of the presentinvention, depending on initial set-up and user choice, and ignores thecompatibility with the existing receiver and initializes the memoryvalue of the trellis encoder (540) for the entire stuff bytes.

In addition, the known symbol location detector/known data output (670)of the receiver is added with the function corresponding to the addedfunction of the parity reconstruction (535) of the transmitter.

The value of the part that initializes the memory value of the trellisencoder of the particular sequence, which is generated in thereplacement sequence generator (513) and replaces the stuff bytes in thestuff byte replacer (515), can be any value. The replacement sequencegenerator (513) considers the symbol value, mapped aftertrellis-encoding according to the memory value to have the desiredpattern by the sequence of the known data wants after theinitialization, and generates the particular sequence to replace thestuff bytes.

The replacement sequence generator (513) stores the above particularsequence in the memory (now shown) and is controlled to adjust the syncby a control signal generator (570). Accordingly, the sequence of theknown data improves the operation performance of the equalizer and thereceiver.

As above-described, stuff bytes are generated and inserted in an MPEG-2TS packet, the inserted stuff bytes are transmitted as known data fromthe digital broadcasting transmitter and the digital broadcastingreceiver detects and uses the known data so that reception performancesuch as sync acquisition and equalization performance can be improved.

In addition, the sequence of the known data improves the operationperformance of the equalizer so that the reception performance of thereceiver can also be improved.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A digital broadcast receiver, comprising: a tuner to receive a datastream including known data and information used to recognize the knowndata; and a processor to process the data stream using the known data,wherein the known data are generated and are inserted into the datastream in a digital broadcast transmitter.
 2. The receiver according toclaim 1, wherein the data stream is transmitted from the digitalbroadcast transmitter comprising a Trellis encoder to perform Trellisencoding using internal memories and to reset the internal memories at apredetermined time point according to a control signal for controllingTrellis reset.
 3. The receiver according to claim 2, wherein the knowndata are generated by a known data generator of the digital broadcasttransmitter, and is inserted into a predetermined location of the datastream by a known data inserting unit of the digital broadcasttransmitter according to a control signal for controlling a process ofinserting known data.
 4. The receiver according to claim 2, wherein anRS parity of the data stream is compensated by an RS encoder included inthe digital broadcast transmitter to correspond to the memory resetting.5. The receiver according to claim 1, wherein the processor comprises: ademodulator; an equalizer; and a known data detector to detect the knowndata from the data stream using the information, and provide at leastone of the demodulator and the equalizer with the detected data stream.6. The receiver according to claim 5, wherein the processor furthercomprises: a Trellis decoder to perform Trellis decoding on the datastream processed by the equalizer; a de-interleaver to performde-interleaving on the Trellis decoded data stream; a Reed-Solomon (RS)decoder to perform RS decoding on the de-interleaved data stream; and areverse-randomizer to perform reverse-randomizing on the RS decoded datastream.
 7. The receiver according to claim 1, wherein the data stream isprocessed to be robust against errors.
 8. A method for processing astream of a digital broadcast receiver, the method comprising: receivinga data stream including known data and information used to recognize theknown data; and processing the data stream using the known data, whereinthe known data are generated and are inserted into the data stream in adigital broadcast transmitter.
 9. The method according to claim 8,wherein the data stream is transmitted from the digital broadcasttransmitter comprising a Trellis encoder to perform Trellis encodingusing internal memories and to reset the internal memories at apredetermined time point according to a control signal for controllingTrellis reset.
 10. The method according to claim 9, wherein the knowndata are generated by a known data generator of the digital broadcasttransmitter, and is inserted into a predetermined location of the datastream by a known data inserting unit of the digital broadcasttransmitter according to a control signal for controlling a process ofinserting known data.
 11. The method according to claim 9, wherein an RSparity of the data stream is compensated by an RS encoder included inthe digital broadcast transmitter to correspond to the memory resetting.12. The method according to claim 8, wherein the processing comprises:demodulating the data stream; equalizing the demodulated data stream;and detecting the known data from the data stream using the information,wherein at least one of the demodulating and equalizing uses thedetected known data.
 13. The method according to claim 12, wherein theprocessing further comprises: performing Trellis decoding on theequalized data stream; performing de-interleaving on the Trellis decodeddata stream; performing RS decoding on the de-interleaved data stream;and performing reverse-randomizing on the RS decoded data stream. 14.The method according to claim 8, wherein the data stream is processed tobe robust against errors.